JPH1054294A - Misfire detecting device for multiple cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an opposed cylinder misfire with high accuracy by adding the difference between angular velocity deviation between two cylinders with continuous explosion strokes computed by a rotational fluctuation quantity computing means, and the preceding angular velocity deviation between two cylinders, and comparing the added value with the judgment value. SOLUTION: In a V-type six-cylinder engine 1, the explosion strokes of No.1 and No.4 cylinders, No.2 and No.5 cylinders, and No.3 and No.6 cylinders appear every 360 deg. CA. An ECU 10 therefore measures required time ΔT within 120 deg. CA from 30 deg. CA after the compression top dead center to 150 deg. CA after the compression top dead center on the explosion stroke of each cylinder. On the No.1 and No.4 cylinders, for instance, rotational fluctuation ΔT360 every 360 deg. CA is obtained by adding ΔT1=T1-T2, ΔT4=T4-T5, and ΔT360 is compared with the predetermined judgment value. In case of ΔT360 being larger than the judgment value as a result of this comparison, generation of an opposed cylinder misfire is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection device for an internal combustion engine, and more particularly to a misfire detection device for a multi-cylinder internal combustion engine.

[0002]

BACKGROUND OF THE INVENTION average rotational speed of the deviation of each cylinder explosion stroke is continuous with _{(ω n-1 -ω n)} , which from 360 ° CA before consecutive average engine speed deviation of each cylinder (omega _{n- 4} −ω _n-3 )
Δω _n = (ω _n−4 −ω _n−3 ) − (ω _n−1 −
An apparatus for determining a misfire by calculating an average rotational speed fluctuation amount from ω _n ) and comparing this with a misfire determination value is known (see Japanese Patent Application Laid-Open No. 4-365958).

However, in the above method, there is a problem that misfires repeated every rotation, that is, every 360 ° CA are canceled out and cannot be detected. For example, FIG.
In (A), 6 of # 1, # 2, # 3, # 4, # 5, # 6
And the ignition order is # 1 → # 2 → # 3 → # 4 →
The explosion stroke of the V6 engine, which is changed from # 5 to # 6, is indicated by hatching.
Cylinder and # 4 cylinder, # 2 cylinder and # 5 cylinder, # 3 cylinder and # 6
The cylinder explosion stroke appears every 360 ° CA. Therefore, the # 1 cylinder and the # 4 cylinder, the # 2 cylinder and the # 5 cylinder, the # 3 cylinder and the # 6 cylinder misfire at 360 ° CA, respectively.
Such a misfire cannot be detected by the above device.
It should be noted that such a misfire that occurs every 360 ° CA is referred to as a facing cylinder misfire.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a misfire detecting device capable of accurately detecting an on-cylinder misfire that repeats every 360 ° CA.

[0005]

According to the first aspect of the present invention, there is provided an angular velocity detecting means for detecting an angular velocity of rotation of a crankshaft during combustion of each cylinder, and an angular velocity detecting means for detecting an angular velocity between two cylinders having a continuous explosion stroke. By calculating the deviation, the first
First rotation fluctuation amount calculating means for calculating the rotation fluctuation amount, and a rotation angle of 360 ° C. more than the timing at which the first rotation fluctuation amount calculating means detects the angular velocity for calculating the first rotation fluctuation amount.
A second rotational fluctuation amount calculating means for calculating a second rotational fluctuation amount by calculating a deviation of the angular velocity between the two cylinders before A, and a first rotational fluctuation amount calculated by the first rotational fluctuation amount calculating means. An adding means for adding the second rotation variation calculated by the two-rotation variation calculation means; and 360 ° comparing the rotation variation added by the addition means with a predetermined determination value.
There is provided a misfire detection device for a multi-cylinder internal combustion engine including a misfire detection means for detecting a misfire occurring for each CA. In the misfire detection apparatus for a multi-cylinder internal combustion engine configured as described above,
The difference between the angular velocity deviation between the two cylinders in which the explosion stroke calculated by the rotation fluctuation amount calculating means is continuous and the angular velocity deviation between the two cylinders 360 ° CA before that calculated by the second rotation fluctuation amount calculating means. The difference is added by the adding means, and the added value is compared with a predetermined determination value by 360 °.
The misfiring of the opposite cylinder occurring for each CA is detected.

According to a second aspect of the present invention, there is provided a misfire detection apparatus for a multi-cylinder internal combustion engine, wherein the misfire detection means has a determination value for each cylinder group that generates a misfire every 360 ° CA. Provided. In the misfire detection device configured as described above, the on-coming cylinder misfire is detected by comparing with a determination value set for each cylinder group.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a misfire detection device according to the present invention. In FIG. 1, reference numeral 1 denotes a V-type six-cylinder engine mounted on an automobile, and # 1
The cylinders # 3 and # 5 are arranged, and the other banks # 2 and # 5
The cylinders # 4 and # 6 are arranged. The engine 1 is provided with an ignition plug 8 for each cylinder.
The order is 1 → # 2 → # 3 → # 4 → # 5 → # 6. Engine 1
Has an intake passage 2, and an air flow meter 4 for detecting an amount of intake air introduced from an air cleaner 3 and a throttle valve 5 are arranged in the intake passage 2. Reference numeral 6 denotes a crank angle sensor that detects the rotation of the crankshaft of the engine 1. Reference numeral 7 denotes a reference position sensor that generates a reference position signal of the crankshaft from the rotation of the camshaft. That is, a reference position signal is generated at the compression top dead center of the # 1 cylinder every 720 ° CA. Reference numeral 10 denotes an engine control unit (hereinafter referred to as an ECU). The ECU 10 includes a digital computer, and includes an input interface 11, a CPU 12, a RAM 13, a ROM 14, and an output interface 15 which are interconnected. The CPU 12 performs an after-mentioned calculation based on the signals of the air flow meter 4, the crank angle sensor 6, and the reference position sensor 7 input through the input interface 11 to perform the opposed cylinder misfire detection of the present invention. Many controls are performed, including basic control such as control of fuel injection amount and control of ignition timing. Many sensors other than those described above are attached to the engine 1 and the like, but they are not shown.

FIG. 2 is a time chart for explaining the operation of the embodiment of the present invention. FIG. 2A shows a case where the compression top dead center of the # 1 cylinder of the engine 1 is 0 ° CA. It shows the appearance timing and order of the explosion stroke of each cylinder. In FIG. 2A, the hatched portion indicates the explosion stroke in each cylinder. As described above, the explosion strokes of the # 1 cylinder and the # 4 cylinder, the # 2 cylinder and the # 5 cylinder, the # 3 cylinder and the # 6 cylinder appear every 360 ° C. Then, for the explosion stroke of each cylinder, from 30 ° CA after the compression top dead center to 1 after the compression top dead center.
Measure the time required between 120 ° CA up to 50 ° CA. The angular velocity referred to in the claims is the reciprocal of the required time. However, since it is easier to execute the calculation for detecting misfire as it is during the required time, in the embodiment described later, the angular velocity is not corrected. The following description will be made without correcting the angular velocity.

FIG. 2B shows the transit time required during the above-mentioned 120 ° CA during each explosion stroke. Assuming that the crank angle scale is at the time indicated by the arrow at this time, what is shown in FIG. 2B at the present time is 120 ° indicated by C1 in FIG. 2A. Time T1 required to pass between CAs. T1 is the T1 = T120 _i in that the value of the currently shown. T2 is the time required for passing through the 120 ° CA during the explosion stroke of the # 6 cylinder that exploded before that, and corresponds to C2, and T2 = T120i _-1 . Similarly, T3 further includes the aforementioned 1 during the explosion stroke of the # 5 cylinder that exploded before.
The transit time between 20 ° CA, corresponding to C3,
T3 = T120i _-2 . Similarly, T4 furthermore
120 ° during the explosion stroke of the # 4 cylinder that exploded before that
Time required for transit between CAs, corresponding to C4, T4 =
T120 _i-3 . T5 is the time required for passing through the 120 ° CA during the explosion stroke of the # 3 cylinder that exploded before that, and corresponds to C5, and T5 = T120i _-4 .

FIG. 2C shows the difference between the values shown in FIG. 2B, and ΔT1 = T1−T2 = T120 _i −T120 _i−1 ΔT2 = T2−T3 = T120 _i-1 -T120 _i-2 ΔT3 = T3-T4 = T120 _i-2 -T120 _i-3 ΔT4 = T4-T5 = T120 _i-3 -T120 _i-4, respectively, between two consecutive explosion strokes 120 ° of the
It represents the difference in transit time between CAs. That is, it indicates the rotation fluctuation between the two cylinders that explode continuously.

Therefore, ΔT4 is 360 times larger than ΔT1.
It shows the rotation fluctuation before ° CA. Then, as shown in FIG. 2C, in this case, the values of ΔT4 and ΔT1 are large, which means that a large rotational fluctuation occurs every 360 ° CA, and that the opposing cylinder misfire has occurred. Is shown. Here, as shown in the prior art, ΔT4 and ΔT1
, The value becomes smaller, ΔT4 and ΔT4
It becomes indistinguishable from the difference when T1 is both a small value and a medium value, and although ΔT4 and ΔT1 themselves become large values and indicate the occurrence of the opposing cylinder misfire, This makes it impossible to indicate that a misfire has occurred in the opposed cylinder. Therefore, in the present invention, the rotation fluctuation [Delta] T ₃₆₀ of each 360 ° CA, by adding the Delta] T1 and .DELTA.T4, i.e., determined at ΔT ₃₆₀ = ΔT1 + ΔT4, the [Delta] T ₃₆₀
Is compared with a predetermined determination value, and if it is larger than the determination value, it is determined that the on-cylinder misfire has occurred.

By the way, as in this embodiment, in a six-cylinder engine, the ignition sequence is # 1, # 2, # 3, # 4, # 5.
→ In the case of # 6, as described above, # 1 cylinder and # 4 cylinder,
Opposed cylinder misfires may occur in cylinders # 2 and # 5, and in cylinders # 3 and # 6. Here, # 1 cylinder and # 4 cylinder are the first cylinder group, # 2 cylinder and # 5 cylinder are the second cylinder group, #
When the three cylinders and the # 6 cylinder are defined as a third cylinder group, when the engine speed NE is low, the opposing cylinder misfire of the first cylinder group, the opposing cylinder misfire of the second cylinder group, and the opposition of the third cylinder group The cylinder misfire also has a large difference from the normal state (the S / N ratio is large), so that it is easy to make a determination, and a common determination value can be used as the above-mentioned determination value. On the other hand, when the engine speed NE is large, the difference between the normal state and the normal cylinder misfire of the first cylinder group, the opposite cylinder misfire of the second cylinder group, and the opposite cylinder misfire of the third cylinder group, respectively. Since a common determination value is used, a misfire in a certain group, for example, the opposing cylinder in the first cylinder group can be detected, but a misfire in the second cylinder group and the third cylinder group can be detected.
In some cases, misfiring of the cylinder group in the opposite cylinder cannot be detected.

Therefore, in this embodiment, a common determination value L at low rotation speed (for example, less than 2500 rpm), a determination value M for the first cylinder group at high rotation speed (for example, 2500 rpm or more), The determination value N for the second cylinder group and the determination value O for the third cylinder group at the time of high rotation are previously determined by an experiment based on the rotational speed NE.
And a map obtained for each air amount GN indicating load and ROM1
4 is stored in, at the time of low rotation comparing the [Delta] T _{36 0} common decision value L irrespective of the cylinder group, in accordance with the cylinder group at the time of high rotation, the determination value M, N, O and the [Delta] T ₃₆₀ In comparison, if ΔT ₃₆₀ is larger than each determination value, it is determined that the opposing cylinder misfire has occurred, and if it is smaller, it is determined that the opposing cylinder misfire has not occurred. FIG. 3 shows the above-described common determination value L for low rotation, and FIG. 4 shows maps M, N, and O of the determination values for each cylinder group for high rotation. By dividing the judgment values as described above, the ROM 14
Is prevented from increasing.

Hereinafter, a routine for detecting a misfiring in the opposite cylinder, which is executed in the ECU 10 based on the above concept, will be described in more detail with reference to flowcharts shown in FIGS. This routine is interrupted every 30 ° CA. In step 1, the current interrupt timing is 30 ° CA, 150 ° CA, 270 ° CA, after the top dead center of cylinder # 1 which the reference position sensor 7 transmits every 720 ° CA.
It is determined whether it is at 390 ° CA, 510 ° CA, or 630 ° CA. This is to be a starting point of rotation fluctuation measurement. If the current interrupt timing is not at the above-mentioned time, the present routine is terminated.

In step 2, the value of the timer, which was reset at the time of the previous interruption, at the time of this interruption is set to T1.
And resetting, and start measuring the time required for 120 ° CA until the next interrupt. In step 3, other various parameters required for the operation of this routine are read. The time T stored in the RAM 13 during the previous 120 ° CA is stored therein.
2. The time T before the previous 120 ° CA
3, the time T4 before the previous 120 ° CA,
Values such as the engine speed NE and the intake air amount GN are included.

In step 4, ΔT1 is obtained by subtracting T2 from T1. Step 5 In by adding ΔT1 and .DELTA.T4, but obtains the [Delta] T _360, where, .DELTA.T4 is 3
The value used as ΔT1 in the previous execution is RA as ΔT4.
Since the value is stored in M13, the value is read and used.

In the next step 6, it is determined which of the cylinder groups the currently executing routine is to detect the misfire of the opposite cylinder. This is performed in detail as follows. The rotor (not shown) of the crank angle sensor 6 attached to the crankshaft is provided with a protrusion every 30 ° CA, and generates 24 pulses in two revolutions of the engine. A crank angle counter (not shown) is provided inside the ECU 10, and the count value CCRNK of the crank angle counter is reset to 0 (by the signal of the reference position sensor 7) by the compression TDC of the # 1 cylinder. Every 30 ° CA, the count is incremented by one each time a pulse is input. Therefore, the possible range of CCRNK is 0 ≦ CCRNK ≦ 23.

Then, the cylinder group is determined as follows. If the current CCRNK <12, set CCRNK to 4
The value of the integer part of the value divided by is CYLW, and CYLW =
The case of 1 indicates the first cylinder group, and CYLW = 2
Indicates that the cylinder group is the second cylinder group, and CYLW = 0 indicates that the cylinder group is the third cylinder group. For example, CCRN
When K = 7, the value obtained by dividing the value is 1.75, and CYLW = 1, so that the calculation for detecting the misfiring of the opposed cylinder group of the first cylinder group is being executed. Become.

If CCRNK ≧ 12, the value obtained by subtracting 3 from the integer part of the value obtained by dividing CCRNK by 4 is defined as CYLW. If CYLW = 1, the first value is defined as CYLW.
CYLW = 2 indicates a cylinder group, and CYLW = 2 indicates a second cylinder group, and CYLW = 0 indicates a third cylinder group. For example, if CCRNK = 14, the value obtained by dividing it by 4 is 3.5, the integer part is 3, and CYLW = 3 obtained by subtracting 3 from the integer.
Since it is 0, it means that the calculation for detecting the misfire of the opposed cylinder group of the third cylinder group is being executed. FIG. 6 is a time chart for explaining the cylinder group determination.

As described above, the cylinder group is determined in step 6, and as a result, when it is determined that the cylinder group is the first cylinder group, the process proceeds to step 7, and when it is determined that the cylinder group is the second cylinder group, step 8 is performed.
If it is determined that the cylinder group is the third cylinder group, the process proceeds to step 9 and it is determined whether the rotation speed is low or high. In this embodiment, the rotation speed is low when the rotation speed is less than 2500 rpm, and the rotation speed is high when the rotation speed is 2500 rpm or more.

If the determination in step 7 is YES, that is, if it is the first cylinder group and the engine is running at a high speed, the process proceeds to step 10, where the determination value S is determined according to the value of the rotational speed NE and the load GN at that time. The determination value for the first cylinder group is mapped to the map M
If the answer is NO and the rotation is low, the process proceeds to step S13, and the above-mentioned common determination value for low rotation is mapped to the determination value S according to the value of the rotation speed NE and the load GN at that time in the map L.
Read from Similarly, for the second cylinder group, the determination value for the second cylinder group is read from the map N in step 11 in the case of high rotation, and the common determination value is read from the map L in step 14 in the case of low rotation in the case of low rotation. Read. Similarly, for the third cylinder group, the determination value for the third cylinder group is read from the map O in step 12 in the case of high rotation, and the common determination value is read from the map L in step 15 in the case of low rotation in the case of low rotation. Read.

The following steps 16 to 24 are steps for correcting the value of ΔT ₃₆₀ obtained in step 5. The GA of steps 16, 17, and 18 is set to T by acceleration or deceleration.
120 is for correcting the change. Where G
A is the rotation fluctuation ΔT14 of the first cylinder group, ie, the # 1 and # 4 cylinders, the rotation fluctuation ΔT25 of the second cylinder group, ie, the # 2 and # 5 cylinders, and the rotation of the third cylinder group, ie, the # 3 and # 6 cylinders. The arithmetic mean of the variation ΔT36, ie, 3
Divided by That is, GA = (ΔT14 + ΔT
25 + ΔT36) / 3, which corrects the change in T120 due to acceleration or deceleration.

The next steps 19, 20, 21 are RAM
13, the correction values GR14, GR25, GR
36 is read. This correction value is for removing the influence of the deviation of the tooth width of the rotor of the crank angle sensor, and the influence of the tooth width of the rotor differs for each cylinder group. Correction value is R
It is stored in AM13.

This correction value is a learning value obtained by a separate routine from the rotation fluctuation at the time of fuel cut during deceleration, which has no influence of combustion and shows only the influence of the tooth width deviation of the rotor of the crank angle sensor. Correction value GR for first cylinder group
14, the correction value GR25 for the second cylinder group and the correction value GR36 for the third cylinder group are GN14 = ΔT14−GA, GN2
Assuming that 5 = ΔT25−GA and GN36 = ΔT36−GA, the following is shown.

GR14 = GR14 + (GR14-GN14) / 4 GR25 = GR25 + (GR25-GN25) / 4 GR36 = GR36 + (GR36-GN36) / 4 Since GR14 + GR25 + GR36 = 0, GR36 =-(GR14 + GR25). is there.

After correcting ΔT ₃₆₀ obtained in step 5 in steps 16 to 24, steps 25, 26,
Proceed to 27. At steps 25, 26, and 27, the ΔT ₃₆₀ corrected as described above and the above steps 10, 1
In steps 1, 12 or in steps 13, 14, 15, a comparison operation is performed with S read from the corresponding maps.

YES at steps 25, 26 and 27 above
Is determined, that is, if the corrected ΔT ₃₆₀ is larger than the determination value, it means that the on-coming cylinder misfire has occurred.
At 0, the misfire counters C14, C25, and C36 that count the number of misfires for each cylinder group are incremented by one. On the other hand, when the determination is NO in steps 25, 26, and 27, that is, ΔT corrected from the determination value
_{If 360} is small, it means that no on-cylinder misfire has occurred.
The process proceeds to step 31 without passing through to update T2 by adding T1 to the next execution of the routine by the interrupt processing, and further proceeds to step 32, where ΔT2, ΔT3,.
ΔT4 is updated by inserting ΔT1, ΔT2, and ΔT3, and the routine ends.

In this routine, the occurrence of a misfire is detected, and in steps 28, 29 and 30, a misfire counter C14,
Although the operation after the values of C25 and C36 are incremented is not particularly described, for example, the counter C1
It can be added that the alarm lamp is turned on when the values of 4, C25, and C36 each become larger than a predetermined number of times. By providing a misfire counter for each cylinder group, it is possible to easily identify which cylinder group is misfiring. As described above, the above-described embodiment can accurately detect the misfiring of the opposed cylinder.

[0029]

According to each of the claims of the present invention, the opposite cylinder misfire is detected with high accuracy by averaging the current rotational fluctuation amount and the rotational fluctuation amount before 360 ° CA and comparing the value with the judgment value. Is done. In particular, if the determination value is set for each cylinder group, the accuracy of the determination is further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the embodiment.

FIG. 3 is a determination value map common to cylinder groups for low rotation.

FIG. 4 is a high-speed determination value map prepared for each cylinder group.

FIG. 5 is a flowchart illustrating an operation of misfire detection performed by an ECU.

FIG. 6 is a flowchart illustrating an operation of misfire detection performed by an ECU.

FIG. 7 is a flowchart illustrating an operation of misfire detection performed by an ECU.

FIG. 8 is a diagram for explaining determination of a cylinder group.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake passage 4 ... Air flow meter 6 ... Crank angle sensor 7 ... Reference position sensor 10 ... ECU

Claims (2)

[Claims] An angular velocity detecting means for detecting an angular velocity of rotation of a crankshaft during combustion of each cylinder, and a first rotational fluctuation amount is calculated by obtaining a deviation of an angular velocity between two cylinders having a continuous explosion stroke. A first rotational fluctuation amount calculating means, and a deviation of the angular velocity between the two cylinders 360 ° CA before the timing at which the first rotational fluctuation amount calculating means detects the angular velocity for calculating the first rotational fluctuation amount. And a second rotation fluctuation amount calculating means for calculating a second rotation fluctuation amount by calculating the first rotation fluctuation amount and a second rotation fluctuation amount calculated by the first rotation fluctuation amount calculating means. Adding means for adding the rotation fluctuation amount; and misfire detection means for comparing the rotation fluctuation amount added by the addition means with a predetermined determination value to detect a misfire occurring every 360 ° CA. Feature Misfire detection apparatus for a multi-cylinder internal combustion engine. 2. The misfire detection device for a multi-cylinder internal combustion engine according to claim 1, wherein said misfire detection means has a judgment value for each cylinder group which generates a misfire every 360 ° CA.